Low-affinity receptor for leukotrienes including leukotriene B4. Mediates chemotaxis of granulocytes and macrophages. The response is mediated via G-proteins that activate a phosphatidylinositol-calcium second messenger system. The rank order of affinities for the leukotrienes is LTB4 > 12-epi-LTB4 > LTB5 > LTB3.
Combining with a leukotriene to initiate a change in cell activity. Leukotrienes are pharmacologically active substances with a set of three conjugated double bonds; some contain a peptide group based on cysteine.
The directed movement of a motile cell or organism, or the directed growth of a cell guided by a specific chemical concentration gradient. Movement may be towards a higher concentration (positive chemotaxis) or towards a lower concentration (negative chemotaxis).
Leukotriene B(4) is a potent lipid mediator known to be implicated mainly in inflammatory actions. Previous pharmacological studies indicated the existence of only one class of G protein-coupled receptor for leukotriene B(4), for which a candidate gene, namely BLT, had been identified. Here we report the isolation of another gene encoding a functional G protein-coupled receptor for leukotriene B(4), named JULF2. JULF2 is a novel G protein-coupled receptor of 358 amino acids that shares 36.6% amino acid identity with human BLT. According to genomic information, the JULF2 gene is located on the chromosome 14, about 4 kilobases upstream of the BLT gene. During screening of endogenous ligands for JULF2, we found that leukotriene B(4) induced inhibition of forskolin-stimulated cAMP accumulation in Chinese hamster ovary cells, stably expressing JULF2. Additionally, Chinese hamster ovary cells expressing exogenous JULF2 showed chemotactic responses with leukotriene B(4) in a pertussis toxin-sensitive manner. A large amount of JULF2 mRNA was detected in the human spleen and the peripheral blood leukocytes. Furthermore, JULF2 mRNA was expressed in mononuclear lymphocytes, in which BLT mRNA was barely detected. The discovery of this second leukotriene B(4) receptor will eventually lead to a better understanding of the classification of leukotriene B(4) receptors and reconsideration of the pathophysiological role of leukotriene B(4).
Leukotriene B(4) is a potent lipid mediator known to be implicated mainly in inflammatory actions. Previous pharmacological studies indicated the existence of only one class of G protein-coupled receptor for leukotriene B(4), for which a candidate gene, namely BLT, had been identified. Here we report the isolation of another gene encoding a functional G protein-coupled receptor for leukotriene B(4), named JULF2. JULF2 is a novel G protein-coupled receptor of 358 amino acids that shares 36.6% amino acid identity with human BLT. According to genomic information, the JULF2 gene is located on the chromosome 14, about 4 kilobases upstream of the BLT gene. During screening of endogenous ligands for JULF2, we found that leukotriene B(4) induced inhibition of forskolin-stimulated cAMP accumulation in Chinese hamster ovary cells, stably expressing JULF2. Additionally, Chinese hamster ovary cells expressing exogenous JULF2 showed chemotactic responses with leukotriene B(4) in a pertussis toxin-sensitive manner. A large amount of JULF2 mRNA was detected in the human spleen and the peripheral blood leukocytes. Furthermore, JULF2 mRNA was expressed in mononuclear lymphocytes, in which BLT mRNA was barely detected. The discovery of this second leukotriene B(4) receptor will eventually lead to a better understanding of the classification of leukotriene B(4) receptors and reconsideration of the pathophysiological role of leukotriene B(4).
Receptors which transduce extracellular signals across the cell membrane. At the external side they receive a ligand (a photon in case of opsins), and at the cytosolic side they activate a guanine nucleotide-binding (G) protein. These receptors are hydrophobic proteins that cross the membrane seven times.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.